// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/filters/ffmpeg_h264_to_annex_b_bitstream_converter.h"

#include <stdint.h>

#include "base/logging.h"
#include "media/ffmpeg/ffmpeg_common.h"
#include "media/formats/mp4/box_definitions.h"

namespace media {

FFmpegH264ToAnnexBBitstreamConverter::FFmpegH264ToAnnexBBitstreamConverter(
    AVCodecContext* stream_codec_parameters)
    : configuration_processed_(false)
    , stream_codec_parameters_(stream_codec_parameters)
{
    CHECK(stream_codec_parameters_);
}

FFmpegH264ToAnnexBBitstreamConverter::~FFmpegH264ToAnnexBBitstreamConverter() { }

bool FFmpegH264ToAnnexBBitstreamConverter::ConvertPacket(AVPacket* packet)
{
    std::unique_ptr<mp4::AVCDecoderConfigurationRecord> avc_config;

    if (packet == NULL || !packet->data)
        return false;

    // Calculate the needed output buffer size.
    if (!configuration_processed_) {
        if (!stream_codec_parameters_->extradata || stream_codec_parameters_->extradata_size <= 0)
            return false;

        avc_config.reset(new mp4::AVCDecoderConfigurationRecord());

        if (!converter_.ParseConfiguration(stream_codec_parameters_->extradata, stream_codec_parameters_->extradata_size, avc_config.get())) {
            return false;
        }
    }

    uint32_t output_packet_size = converter_.CalculateNeededOutputBufferSize(
        packet->data, packet->size, avc_config.get());

    if (output_packet_size == 0)
        return false; // Invalid input packet.

    // Allocate new packet for the output.
    AVPacket dest_packet;
    if (av_new_packet(&dest_packet, output_packet_size) != 0)
        return false; // Memory allocation failure.

    // This is a bit tricky: since the interface does not allow us to replace
    // the pointer of the old packet with a new one, we will initially copy the
    // metadata from old packet to new bigger packet.
    av_packet_copy_props(&dest_packet, packet);

    // Proceed with the conversion of the actual in-band NAL units, leave room
    // for configuration in the beginning.
    uint32_t io_size = dest_packet.size;
    if (!converter_.ConvertNalUnitStreamToByteStream(
            packet->data, packet->size,
            avc_config.get(),
            dest_packet.data, &io_size)) {
        return false;
    }

    if (avc_config)
        configuration_processed_ = true;

    // At the end we must destroy the old packet.
    av_packet_unref(packet);
    *packet = dest_packet; // Finally, replace the values in the input packet.

    return true;
}

} // namespace media
